Discharge apparatus



Aug. 30, 1932. GLHOLST ET AL DISCHARGE APPARATUS F119! lay 28 192 I nve "Con;

I ummnll f I mum/m1 Patented Aug. 30, 1932 UNITED STATES JoF- ca GILLES HOLST am) BALTH-ASAB VAN DER ion or, munnovnu, anagra s, as

srouons TO N. v. rnrmrsz, onomramranranaxnxnm ornmnnovnn LANDS DISCHARGE Application filed ma 2a, 1926, Serial no. 112,280;hnd m tliefltetherlands au dst'is; 192a This invention is based on the principle of subjecting the emission emanatin from a cathode to the influence of a space 0 arge due to an additional cathode whichis disposed within the same dischar e tube and is so arranged relatively to the rst mentioned cathode that the electrons emanating from it, in so far as they do not strike intermediate electrodes, constitute a so-called cloud on re versal of their direction of movement adj acent the first mentioned cathode.

If between the said two cathodes which hereinafter for convenience sake will be referred to as the innermost one and the outermost one respectively, a grid is arranged which serves as an anode for both cathodes, it can be ensured that at an increasing potential difference between the anode on the one hand and the cathode on the other hand the hindering influence exercised by the space charge of the outermost cathode on the emission of the innermost one is more intense than the influence of the increase of the anode potential on the said emission; In these circumstances the-current flowing from the anode to the innermost cathode decreases consequently at an increasing potential difterence between the said two elements so that the device can operate with a negative resistance characteristic and can be used for generating oscillations.

Preferably the device according to the invention comprises an exhausted bulb in which are concentrically arranged a central incandescent cathode, a grid-shaped anode and an enveloping cathode.

According to the invention this latter cathode is moreover preferably constructed as an equipotential cathode.

The invention will hereinafter be set out more clearly by reference to the diagrammatic drawing accompanying the specifica-' tion.

In the said drawing:

Figure 1 shows diagrammatically a method of arranging the electrodes according to the invention.

Figure 2 shows in vertical section a socalled stem provided with electrodes arranged as shown in Figure 1.

:a central incandescent Cathdde 1 which is shown in the form of a'wire is surrounded by an; anode 2 which is perforated or 1 otherwise provided-with apertures. The said a anode may 'consist,wforexample,- in the manner known for grids, of a 'helically wound metal "wire as shown in Figure Around the'ex terior of the anode 2is' mounteda secondelec tron emitting cathode3. The latter may con sist, for example, 'likewise. of a -helically wound Wire heated by the passage ofa current." However, it is. preferable that a socalled equipotential cathode: should be employed in order toprevent'considerable voltage differences between the starting point and the "final point of the said cathode. 1

The *lectronsernanating from the cathode sipartially pass through the anode 2 and from this moment their speed is "slackened until they arrive adjacent the cathode 1 when their direction of movement is reversed. "Thus a 'continuouacloud of electrons is maintained :by. the cathode 3 around the cathode 1, said cloud "intensifying the-space charge at the cathode 1 and thus counter-acting the emission of'the cathode 1.. Themore the cathode .3 emits, for examplethe more 'ositive the anode 2 is relatively to the-cat ode. 3, the greater is the extent to whichthis counteraction occurs-apart from saturation phenomena. 'Now, it has been four dithat thisindinect influence of potential changes ofthe an,- ode 2 on the emission of the cathode 1 can exceed'the direct influence, in other words, that at an increaseof thepot ential'of the anode 2, other circumstances being the same, the emission of the cathode '1 can beweakened by the increasing space charge. due to the cathode 3 to a greater extent than it can be intensified by the increase of the electrostatic field between the anode 2 and the cathode 1.7 Consequently, in a closed circuit in which the anode 2 and the cathode 1 and also a source of voltage are inserted, oscillations can be generated, as the said circuit will show a negative resistance characteristic.

In the construction shown in Figure 2 the incandescent cathode 1 is stretched between two pole wires 4 which are sealed in known manner in a glass stem 5. The anode 2 consists of a helically wound wire having its turns secured to a small carrying rod 6 which merges into supports 7 sealed in the stem 5.

The outermost cathode 3 consists of an open cylinder which is coated on its inner side with an active layer (for example an alkaline earth oxide) and which is secured'in the stem 5 by a carrier 8. The heating is efiected by means of, a resistance wire 9 wound around the said cylinder and insulated therefrom by the insulation Hand to which'current can be supplied by wires 10 which are also led outwardly through the stem 5. The glass en- ;ielope 16 encloses the entire electrode assemya Obviously it'is possible byregulating the temperatures of the two cathodes to intensify the effect in view by providing that at a given potential of the anode 2 a state of saturation has already occurred in the emission at the cathode 1 but not at the cathode 3. When the a otentialaof-the anode 2 increases, the direct influence of the anode 2 on the cathode 1 can a be neglected and the counteracting influence of the increasing emission of the cathode 3 only remains. 7 Although a cylindrical and concentric arrangement of the electrodes is illustrated and described, th'evinvention is by no meanslimited thereto as it is possible to indicate numerous constructions in which the hereinbefore described newprinciple of influencing the emission of a'cathode can be realized by the space charge of one or more other cathodes.

What we claim isi I 7 An electron discharge device comprising a I source of primary electrons, a second source of primary electrons mounted concentrically about the first source, and means concentric with and intermediate these two sources of primary electrons for attracting the electrons from said sources, said means being apertured and positioned withrespect to the two sources for passing electrons from one source through the apertures and thereby afiecting the eIIllSSlOIl of electrons from the other source. 7 V

' In testimony whereof we aflix oursigna- Z tures, at the city of Eindhoven, this 11th day of May, A. D. 1926. r I 1 A GILLES HOLST. BALTHASAR VAN DER POL. 

